Blood test could predict kidney transplant rejection

UK researchers have found a way to predict rejection of a kidney transplant before it happens, by monitoring the immune system of transplant patients. Their research has been published in the journal EBioMedicine.

A renal transplant offers the best treatment for patients whose kidneys have failed, with around 3000 carried out annually in the UK. Acute rejection occurs when the body’s immune system begins to attack the donated organ, and affects around 2 in 10 patients in the first year after the transplant. It can also affect the lifespan of the transplanted organ.

Currently, acute rejection can only be confirmed by taking a biopsy of the transplanted organ. While acute rejection can be treated, this can only be done when the organ is already affected and damage has already occurred.

Researchers from the National Institute for Health Research Biomedical Research Centre, a partnership between Guy’s and St Thomas’ and King’s College London, have now found that a signature combination of seven immune genes in blood samples can predict rejection earlier than current techniques. Monitoring these markers in transplant patients with regular blood tests could help doctors intervene before any damage to the organ occurs, and improve outcomes for patients.

The team recruited 455 patients who received a kidney transplant at Guy’s Hospital and followed these patients over the first year of their transplant, collecting regular blood and urine samples. Using these samples and analysing the data over time, they developed a signature combination of seven genes that differentiated patients who developed rejection from those who did not. They then tested for the signature via a blood test in a separate cohort of patients, and validated that it predicted transplant rejection.

The team also identified a six-gene signature for a less common form of complication. BK-virus nephropathy can look clinically similar to acute rejection, but requires a very different therapy — reducing immunosuppression. Being able to distinguish between these complications would mean clinicians can ensure that patients receive the most appropriate treatment.

Once the new technique is validated further, it has the potential to offer clinicians the use of a simple blood test to predict rejection. Being able to intervene before the event will help prevent damage to patients, and extend the life of the transplanted organ.

“This advance could make a huge difference to our ability to monitor kidney transplant patients and treat rejection earlier,” said Dr Paramit Chowdhury, an author on the paper. “It may also save some patients from an unnecessary biopsy. It is a first step in getting a better insight into the status of a patient’s immune system, allowing better tailoring of the patient’s anti-rejection treatment.

“A big challenge at the moment is that even the best transplanted organ has a limited lifespan of up to 30 years. By being able to pick up signs of rejection early, we might increase the lifespan of the organ and help patients have a better quality of life, for longer.”

Image credit: ©stock.adobe.com/au/Ben Schonewille

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